ice: Implement ice_bridge_getlink and ice_bridge_setlink

ice_bridge_getlink returns the current bridge mode using
ndo_dflt_bridge_getlink and the mode parameter available in
first_switch->bridge_mode.

ice_bridge_setlink is invoked when the bridge mode needs to
changed. The value to be changed to is available as a netlink
message which is parsed in this function. If the mode has to
be changed, switch_flags is set appropriately (set ALLOW_LB
for VEB mode and clear it for VEPA mode) and ice_aq_update_vsi
is called. Also change the unicast switch filter rules.

Signed-off-by: Md Fahad Iqbal Polash <md.fahad.iqbal.polash@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>